1. Field of the Invention
The invention relates in general to the field of food preparation ovens, and specifically to a gas “true” convection oven.
2. Description of the Related Art
Convection ovens have long been popular in the cooking industry for both residential and commercial use. Typically, a gas convection oven involves a heat source disposed underneath the oven cavity, and a fan within the cooking cavity to circulate the hot air in the cooking cavity. This arrangement has the disadvantage that the air being blown through the fan is only as hot as the air within the oven cavity. Thus the heating of the food in the oven is uneven and much of the heat from the heat source is lost.
In order to improve the heating efficiency and increase oven temperatures, it was contemplated to provide a heat source in close proximity to the fan such that the air being moved by the fan is hotter than the air within the oven cavity. Thus food products within the oven are heated uniformly by air of a higher temperature, thus increasing heat transfer efficiency between the air and food products and reducing cooking times. This arrangement is typically termed “true convection” in the cooking appliance industry. Essentially, the term “true convection” refers to an oven in which a burner, or heat source is disposed in close proximity to the fan and that the air passing through the fan and into the oven cavity is at a higher temperature than the air within the oven, thus the heat is convectively transferred from the hot, moving air to the food products within the oven.
Such “true” convection environments are typically created with an electric heat source disposed immediately in front of, behind, or surrounding the convection fan. This convection heat source is typically provided in addition to heat sources for standard non-convective baking. This has the result of significantly increasing the cost of the oven due to the fact that the oven must be adapted to operate multiple heat sources of various type and size. When the standard heat source is a gas burner or broiler, the oven must be adapted to operate with both gas and electrical power. Additionally, it is difficult to install a gas burner in close proximity to the fan, as the turbulence caused by the fan will greatly affect flame stability and emission. It has also been difficult to design a gas burner which can function in both fan-on and fan-off conditions.
It is therefore desirable to create a gas “true convection” cooking environment in an oven without the necessity of multiple heat sources, while providing the ability to draw hot air from a heating source with stable combustion conditions.